Disc valve is a device with the round disc providing opening and closing function, and the rotation of the disc is centered by its axis and cycling along the sealing surface of the valve seat. The application of disc valve covers the polycrystalline silicon, organic silicon and coal chemical industries. The disc is driven by the actuator through the valve stem, and as the movement proceeds, the whole sealing surface of the disc is moving against the sealing seat tightly with the compression of the spring, in case that the granule medium flows into the sealing surface.
As shown in FIG. 1, the known disc valve comprises a hollow cylindrical middle valve body 150, and the left valve body 101 and right valve body 102 are beside each side of the middle valve body 150; in the valve cavity 10, the rotation of sealing disc 140 is controlled by movement of the valve stem 118 through the rod 40 and the spring cavity 52. However, this kind of disc valve has following defects.
1) Prone to accumulating materials in the valve cavity. As in FIG. 2, the valve passage lies in the horizontal direction, and the diameter of the valve body is much larger than that of the passage pipe. Therefore, materials cannot be discharged totally in the opening and closing process so that the materials stay in the valve cavity. Furthermore the valve cannot open and/or close in the right place and even is stuck.
2) Installation direction is limited. When the valve is installed horizontally (as in FIG. 2, the direction of stem is horizontal), the problem of material accumulation is worse. When the valve is vertically installed (as in FIG. 3, the direction of the stem is vertical and the passage is vertical too), the consequence seems better but the problem cannot be solved completely. Material accumulation of the disc valve makes it difficult to arrange pipes or install the valve by considering the influence of installation direction. Horizontal installation is worse than vertical installation with the effect of material accumulation, and upper inlet is worse than bottom inlet when installed obliquely. The best installation requirements cannot be satisfied with the limitation of practical spatial conditions.
3) Large loss of differential pressure. When the materials are flowing from the passage to the valve cavity, the volume of the materials increases so fast that the pressure goes down.
4) Unprotected opening sealing surface. When the valve is in the opening position, the sealing surface of the valve seat is not protected, and is abraded by the material flow, leading to the influence of the sealing effect of the valve and the reduction of its service life.
5) Influence of outer sealing in high temperature conditions. When the cavity touches the high-temperature materials directly, it requires a high quality of the gaskets, and the sealing condition is difficult to implement. Since the service life of the gaskets is limited, the entire valve should be dismounted when changing the bad gaskets.